Three- and five-way low loss phase combiners for power amplifier sharing in cellular networks

Novel low loss 3×3-way and 5×5-way phase combiners for power amplifier load balancing in wireless network cells are presented. Based on an air-filled coaxial multiring structure, the designs combine very low insertion loss with compact physical profile. The concept is studied for the PCS (personal communication service) transmit band in the range 1.91-1.99 GHz by simulation. Measurements validate the predicted very low insertion loss for the three-way combiner of 0.05 dB, while return loss and port isolation are both better than 25 dB. Simulations exhibit, with 0.15 dB insertion loss, a similar performance for the five-way device. Return loss and port isolation are better than 23 dB in this case.